Calls to decolonize or provincialize outer space have emerged in the face of materializing plans to send humans back to the moon and onto Mars on colonizing missions. But the fundamental material differences of other places in the cosmos raise significant anthropological questions—simultaneously empirical and speculative—about the possibilities for any such endeavors in the terrestrial, colonial terms and conditions in which they are set, all of them predicated by the stabilizing conditions of Earth’s gravity, atmosphere, core, moon, and more. I argue that any terrestrial epistemic, ideological, or conceptual framework—capitalism, colonialism, extraction, system, hierarchy...—that is not transformed in active relation to the material conditions of the cosmic otherwheres they reach out to will inevitably fail—but that the same is also true of decolonization. As such, I argue that the material variation and variability of the cosmos demands a transformed conceptualization of decolonization. In this paper, I suggest that ostensible space colonists could only survive—and even thrive—in a mode of permanent cosmic decolonization, even as the terrestrial intellectual, ethical, and political precedents of decolonization—and its fundamental, radical openness to difference and possibility—remains the best terrestrial starting place for thinking anthropologically about the nonterrestrial cosmos.